vite-node's import.meta.hot.accept does not work

[lukadev-0]

Describe the bug

Any import.meta.hot.accept function will break HMR and the function passed to accept is never called.

I've figured out the cause of this bug by modifying the module in node_modules and adding some console logs, here is what I've found.

vitest/packages/vite-node/src/hmr/hmr.ts

Lines 105 to 114 in b7ce195

	async function fetchUpdate(runner: ViteNodeRunner, { path, acceptedPath }: Update) {
	const maps = getCache(runner)
	const mod = maps.hotModulesMap.get(path)
	if (!mod) {
	// In a code-splitting project,
	// it is common that the hot-updating module is not loaded yet.
	// https://github.com/vitejs/vite/issues/721
	return
	}

The problem is within this function, the mod variable will always return undefined. This is because the path within the update is relative to the project root, so if your project is within /home/me/my-project and you had a file named main.js within that directory, the update's path property would be /main.js.

However, the hotModulesMap's keys are added here:

vitest/packages/vite-node/src/hmr/hmr.ts

Line 248 in b7ce195

maps.hotModulesMap.set(ownerPath, mod)

The ownerPath parameter is given in the runner:

vitest/packages/vite-node/src/client.ts

Line 375 in b7ce195

hotContext ||= this.options.createHotContext?.(this, `/@fs/${fsPath}`)

The fsPath is an absolute path to the file, prepended by /@fs/, which is different from the format given in the Update object, meaning that the mod variable will always be undefined, causing it to do an early return.

Reproduction

https://github.com/lukadev-0/vite-node-hmr-bug

System Info

  System:
    OS: Linux 6.2 Pop!_OS 22.04 LTS
    CPU: (4) x64 AMD Athlon 300GE with Radeon Vega Graphics
    Memory: 913.02 MB / 5.71 GB
    Container: Yes
    Shell: 5.8.1 - /usr/bin/zsh
  Binaries:
    Node: 20.3.1 - ~/.nvm/versions/node/v20.3.1/bin/node
    npm: 9.6.7 - ~/.nvm/versions/node/v20.3.1/bin/npm
    pnpm: 8.6.5 - ~/.local/share/pnpm/pnpm
  Browsers:
    Brave Browser: 115.1.56.1

Used Package Manager

pnpm

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